Influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation

We examined the influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation in Mt Gariwang, Pyeongchang, South Korea. In 2014 and 2015, from April to October, we recorded the presence of tracks as a proxy for abundance, for the following seven mammalian species: Korean hare Lepus coreanus, raccoon dog Nyctereutes procyonoides, Siberian weasel Mustela sibirica, Eurasian badger Meles meles, water deer Hydropotes inermis, roe deer Capreolus pygargus, and wild boar Sus scrofa. We also assessed how the intensity of tree thinning affected vegetation cover; there were significant differences in number of standing trees, basal area, coverage of vegetation layers, and number and volume of downed trees among the control, moderately thinned, and intensively thinned stands. We found significant differences in the abundance of tracks among the stands for three mammal species. In four mammal species, the abundance of track was significantly correlated with volume of downed trees, coverage of ground vegetation, number of downed trees, and number of standing trees, according to stepwise analysis. The presence and abundance of mammals is linked to habitat variables and forest managers should consider how habitat modifications will affect wildlife.     

Combining GIS application and climatic factors for mosquito control in Eastern Province,Saudi Arabia

This study aims to determine the effect of climatic factors (temperature, relative humidity and rainfall) on mosquito abundance and to map mosquito larva breeding sites using GIS application in Eastern Province, Saudi Arabia. The data pertaining to larval and adult mosquito abundance/distribution and climatic factors were collected for the study period of 2014. Bi-variate and multivariate analyses were performed to determine the relationship between mosquito abundance and climatic factors (temperature, relative humidity and rainfall). The utilization of GIS with GPS facilitates to identify and map larva breeding sites in the study area. The result showed strong negative correlation between mosquito abundance and temperature while there appeared a strong positive correlation with relative humidity and moderate positive correlation with rainfall. Low mosquito abundance was observed at high temperatures whereas high and moderate mosquito abundance was observed at high humidity and during rainy months, respectively. In the adult mosquito, the regression model for three climatic factors (temperature, RH and rainfall) and other factors showed a variation of 84.5% of the variance accounted for the climatic factors while the remaining 15.5% were attributed to other factors. In larva, 64.3% of the variance accounted for climatic factors, and the remaining 35.7% attributed to other factors such as the presence of vegetation, waste materials and water reservoirs such as ditches. In comparison, the larva seems influenced by the presence of vegetation, waste material, water reservoirs and ditches and less influenced by climatic factors than the adult mosquito. Development of a risk map by considering the flying distance of the adult mosquito from the studied sites showed three major clusters where a recommendation for management control program was suggested.     

Habitat preferences of the urban wall spider Oecobius navus (Araneae, Oecobiidae)

Abstract  To assess the relative impact of a range of habitat variables on spider abundance, field and laboratory experiments were conducted on populations of the urban wall spider Oecobius navus in suburban Perth, Western Australia. Habitat characteristics investigated were: substrate type, wind speed, rainfall, sunlight exposure, relative humidity, air temperature, substrate temperature, artificial lighting and prey type/abundance. In the field, O. navus was found to be associated with high humidity, low air temperature and shelter from sunlight and rainfall. Oecobius navus was more abundant at sites with greater prey abundance. The most common prey item was the red meat ant Iridomyrmex chasei . Juvenile spiders were more abundant than adult spiders; however, patterns between spider abundance and habitat variables were similar for both adults and juveniles. Laboratory experiments showed that O. navus preferred to build webs on wooden substrates, and pitted limestone walls. These findings indicate that O. navus may be vulnerable to desiccation and/or thermal stress, and thus survives better on sheltered walls.     

Environmental factors and community dynamics at the southernmost part of the North American Graminetum – I. On the contribution of climatic factors to temporal variation in species composition

Compositional patterns of vegetation and their relationship to temporal and spatial environmental variation, with emphasis on climatic factors, were investigated in plant communities located in the southernmost portion of the North American Graminetum, in central México. Data from 353 samples, obtained in four ecologically contrasting plant communities during 11 years, were analyzed by partial canonical correspondence analysis. Eight climatic variables and eighteen covariables (seventeen edaphic and one resource management) were included in the ordination. A relationship between floristic change and weather variation, once covariables effects were fitted, was examined. Despite a strong contrast in ecological conditions among study sites, a set of four climatic variables was finally found in which each variable contributed independently and statistically (P < 0.01) to the total variance in the vegetation data. Thus, environmental variables other than climatic could not conceal the important role of weather as a mediator of floristic change through time. Summer precipitation and summer maximum temperature showed the highest correlations with the first two species axes, 0.77 and –0.39, respectively. Contribution of these two climatic variables to variance in the vegetation data explained by environmental variables was approximately 81%. Annual species were abundant during rainy years, while abundance of perennial grasses and shrubs showed no clear relationship to weather variation. This study explicitly probes the important role of rain patterns in shaping structure and composition of semiarid communities and considers how other environmental factors can affect plant communities at the southernmost part of the North American Graminetum.     

The bigger they come, the harder they fall: body size and prey abundance influence predator-prey ratios

Large carnivores are highly threatened, yet the processes underlying their population declines are still poorly understood and widely debated. We explored how body mass and prey abundance influence carnivore density using data on 199 populations obtained across multiple sites for 11 carnivore species. We found that relative decreases in prey abundance resulted in a five- to sixfold greater decrease in the largest carnivores compared with the smallest species. We discuss a number of possible causes for this inherent vulnerability, but also explore a possible mechanistic link between predator size, energetics and population processes. Our results have important implications for carnivore ecology and conservation, demonstrating that larger species are particularly vulnerable to anthropogenic threats to their environment, especially those which have an adverse affect on the abundance of their prey.     

Responses of mammalian carnivores to land use in arid savanna rangelands

Shrub encroachment due to heavy grazing has led to dramatic changes in arid savanna landscape structure worldwide. It is considered to be one of the most threatening forms of rangeland degradation altering plant diversity. However, possible impacts of shrub encroachment on species diversity at higher trophic levels remain poorly understood. Additionally, indirect effects, such as changes of trophic interactions, are often ignored when trying to understand changes in biodiversity patterns. In this study, conducted in the southern Kalahari, we explored how the diversity of small carnivores and their prey is affected by shrub encroachment. We analysed the relationships between abundance and diversity of small carnivores, the availability of their main prey groups (coleopterans, termites, grasshoppers, rodents) and the structural diversity of the landscape (shrub, grass and herb cover). Eight hundred track surveys were conducted to determine carnivore abundance on 20 rangeland habitats, which represented a gradient of grazing intensity. Prey availability was surveyed for each study site and related to vegetation cover.

Results show a significant impact of shrub cover on abundance and diversity of carnivores and their prey. The diversity of both, carnivores and their prey, showed a hump-shaped response to increasing shrub cover whereas relative carnivore abundance decreased. Availability of prey groups was affected differently by shrub cover increase. Diversity of carnivores was best predicted by shrub cover (R²>0.7, p<0.001) indicating the overriding role of habitat structure as compared to prey availability. We conclude that intermediate shrub cover values enrich structural diversity of savanna landscape and in consequence sustain diversity of small carnivores and their prey in arid and semiarid ecosystems.     

Do the antipredator strategies of shared prey mediate intraguild predation and mesopredator suppression?

Understanding the conditions that facilitate top predator effects upon mesopredators and prey is critical for predicting where these effects will be significant. Intraguild predation (IGP) and the ecology of fear are hypotheses used to describe the effects of top predators upon mesopredators and prey species, but make different assumptions about organismal space use. The IGP hypothesis predicts that mesopredator resource acquisition and risk are positively correlated, creating a fitness deficit. But if shared prey also avoid a top predator, then mesopredators may not have to choose between risk and reward. Prey life history may be a critical predictor of how shared prey respond to predation and may mediate mesopredator suppression. We used hierarchical models of species distribution and abundance to test expectations of IGP using two separate triangular relationships between a large carnivore, smaller intraguild carnivore, and shared mammalian prey with different life histories. Following IGP, we expected that a larger carnivore would suppress a smaller carnivore if the shared prey species did not spatially avoid the large carnivore at broad scales. If prey were fearful over broad scales, we expected less evidence of mesopredator suppression. We tested these theoretical hypotheses using remote camera detections across a large spatial extent. Lagomorphs did not appear to avoid coyotes, and fox detection probability was lower as coyote abundance increased. In contrast, white‐tailed deer appeared to avoid areas of increased wolf use, and coyote detection probability was not reduced at sites where wolves occurred. These findings suggest that mesopredator suppression by larger carnivores may depend upon the behavior of shared prey, specifically the spatial scale at which they perceive risk. We further discuss how extrinsic environmental factors may contribute to mesopredator suppression.     

Structural changes of vegetation and its association with microclimate in a successional gradient of low thorn forest in northeastern Mexico

Understanding how microclimate and vegetation are associated during secondary succession is of primary importance for plant conservation in the face of the increasing land cover modification. However, these patterns are still unstudied for many plant communities. This study aimed to evaluate the structure (species richness, Shannon's diversity index, Simpson´s dominance index, abundance of each species, average height of species, species cover (%), species composition, and indicator values) of a low thorn forest fragment and to analyze its relation with microclimate along a successional gradient. Four stages of succession were delimited by the analysis of Landsat images, in the state of Tamaulipas, northeast Mexico. Statistical models incorporated species richness, diversity indices, abundance, height, and cover, as variables for searching differences between stages, or to evaluate microclimate associations. A total of 70 species, 54 genera, and 27 families were determined. Height of tree layer was the most important variable for discrimination of the successional stages. Conserved areas differed floristically from other stages, associated mainly with the lowest values of wind speed originated by tree layer characteristics. A significant association between species and microclimate was found, being wind speed and relative humidity the most important variables. Some species, due to their high importance values and their patterns of association with microclimate, may be considered as key taxa for low thorn forest, which is a threatened semitropical community in northeast Mexico. Conserved and late successional areas account for climatic regulation of this plant community, and the importance of these forest patches may be considered when establishing biodiversity protection areas.

     

Effects of human–carnivore conflict on tiger (Panthera tigris) and prey populations in Lao PDR

Unique to South-east Asia, Lao People's Democratic Republic contains extensive habitat for tigers and their prey within a multiple-use protected area system covering 13% of the country. Although human population density is the lowest in the region, the impact of human occurrence in protected areas on tiger Panthera tigris and prey populations was unknown. We examined the effects of human–carnivore conflict on tiger and prey abundance and distribution in the Nam Et-Phou Louey National Protected Area on the Lao–Vietnam border. We conducted intensive camera-trap sampling of large carnivores and prey at varying levels of human population and monitored carnivore depredation of livestock across the protected area. The relative abundance of large ungulates was low throughout whereas that of small prey was significantly higher where human density was lower. The estimated tiger density for the sample area ranged from 0.2 to 0.7 per 100 km². Tiger abundance was significantly lower where human population and disturbance were greater. Three factors, commercial poaching associated with livestock grazing followed by prey depletion and competition between large carnivores, are likely responsible for tiger abundance and distribution. Maintaining tigers in the country's protected areas will be dependent on the spatial separation of large carnivores and humans by modifying livestock husbandry practices and enforcing zoning.     

Landscape‐scale accessibility of livestock to tigers: implications of spatial grain for modeling predation risk to mitigate human–carnivore conflict

Innovative conservation tools are greatly needed to reduce livelihood losses and wildlife declines resulting from human–carnivore conflict. Spatial risk modeling is an emerging method for assessing the spatial patterns of predator–prey interactions, with applications for mitigating carnivore attacks on livestock. Large carnivores that ambush prey attack and kill over small areas, requiring models at fine spatial grains to predict livestock depredation hot spots. To detect the best resolution for predicting where carnivores access livestock, we examined the spatial attributes associated with livestock killed by tigers in Kanha Tiger Reserve, India, using risk models generated at 20, 100, and 200‐m spatial grains. We analyzed land‐use, human presence, and vegetation structure variables at 138 kill sites and 439 random sites to identify key landscape attributes where livestock were vulnerable to tigers. Land‐use and human presence variables contributed strongly to predation risk models, with most variables showing high relative importance (≥0.85) at all spatial grains. The risk of a tiger killing livestock increased near dense forests and near the boundary of the park core zone where human presence is restricted. Risk was nonlinearly related to human infrastructure and open vegetation, with the greatest risk occurring 1.2 km from roads, 1.1 km from villages, and 8.0 km from scrubland. Kill sites were characterized by denser, patchier, and more complex vegetation with lower visibility than random sites. Risk maps revealed high‐risk hot spots inside of the core zone boundary and in several patches in the human‐dominated buffer zone. Validation against known kills revealed predictive accuracy for only the 20 m model, the resolution best representing the kill stage of hunting for large carnivores that ambush prey, like the tiger. Results demonstrate that risk models developed at fine spatial grains can offer accurate guidance on landscape attributes livestock should avoid to minimize human–carnivore conflict.     

Assessing effects of radiation on abundance of mammals and predator–prey interactions in Chernobyl using tracks in the snow

To test whether radioactive contamination reduced the abundance of mammals, and whether species differed in susceptibility to radiation, we censused mammals by counting tracks in the snow along 161 100-m line transects around Chernobyl during February 2009. The abundance of mammal tracks was negatively related to level of background radiation, independent of the statistical model, with effects of radiation accounting for a third of the variance. The effect of radiation differed significantly among species. There was a positive relationship between abundance of predators and abundance of prey, modified by the level of background radiation because the number of predators increased disproportionately with the number of prey at high levels of radiation. These findings suggest that predatory mammals aggregate in areas with abundant prey, especially when prey are exposed to high levels of radiation. This study emphasizes the negative effects of level of background radiation on the abundance of mammals and predator–prey interactions.     

Culicidae Community Composition and Temporal Dynamics in Guapia?u Ecological Reserve,Cachoeiras de Macacu,Rio de Janeiro,Brazil

A temporal observational study was conducted of the Culicidae fauna in a remnant area of Atlantic Forest within a private reserve (Guapiaçu Ecological Reserve-REGUA) presenting typical vegetation cover of dense rain forest, with some patches recovering a floristic composition similar to that of the original community. Research was carried out to analyze the influence of climatic factors (mean monthly temperature, rainfall, and air relative humidity) on the temporal dynamics of the mosquito communities that occur in the reserve. The completeness of the mosquito inventory was assessed with individual-based rarefaction-extrapolation curves. Differences in species composition between sites and months were tested with PERMANOVA. True diversities of orders 0, 1, and 2 (effective numbers) were estimated and compared between sites, months, and years. Multiple stepwise regressions were used to assess relationships between climatic variables, measures of diversity, and abundances of the most common species. There were significant interactive effects between year and site on measures of diversity. However, diversity estimates showed little variation among months, and these were weakly correlated with climatic variables. Abundances of the most common species were significantly related to temperature or relative humidity, but not rainfall. The presence of mosquito species known to be vectors of human diseases combined with an intermittent flow of visitors to the study area suggests there is a risk of disease transmission that warrants further monitoring.     

CLM3.0-DGVM中植物叶面积指数与气候因子的时空关系

作为陆面模型里植被的特征量,叶面积值数（LAI）和植被覆盖度在陆地-大气相互作用的相关研究里被广泛应用。LAI的模拟是动态植被模式（DVM）的核心任务之一,需要对模拟的LAI与气候因子间的时空关系进行评估以更好的了解模式性能以及理解植被-大气反馈过程。用1950—1999年的气象数据驱动通用陆面模式的动态植被模式（CLM3.0-DGVM）模拟得到的全球潜在植被的LAI和2001—2003年MODIS观测资料衍生出的LAI数据进行对比,并在此基础上研究当前气候条件下不同植物功能型（PFT）的LAI与不同气候因子在年际尺度上的时空关系,包括运用Moran系数理论分析空间自相关性、运用逐步回归算法构建空间最优一阶线性回归方程、分析模式LAI与气候因子间的滞后相关性。研究表明：1）以MODIS衍生数据作参照,改进后的CLM3.0-DGVM能较好地模拟不同PFTs的LAI年最大值的空间分布型,但是在物候模拟即LAI的季节循环上存在不足;2）植物LAI的分布具有正的空间自相关性。对潜在植物LAI和气候因子进行拟合时不同气候因子对不同PFTs的方差贡献不一样,一般降水最大、风速最小。这反映了陆地生态系统和气候间复杂的相互关系;3）模式模拟的LAI和气候因子有显著的1～2年的滞后相关,其中光照、降水和LAI的滞后相关性波动较大,而温度、比湿的较小,风速的不明显。这些基于CLM3.0-DGVM的结论在自然界的植物–气候相互作用系统中具有普遍意义：不同地区不同植物受不同气候因子的影响不一样;找出不同PFT的主要气候影响因子和理解其中最关键的生物物理和生物化学过程是至关重要的。进一步工作需要用更精确和更高分辨率的气候数据以及局地观测的LAI对DGVM做评估,同时DGVM本身也需要继续改进（例如加入农作物和灌溉过程的模拟）。     

Ranging behaviour and activity of red foxes (Vulpes vulpes: Mammalia) in relation to environmental variables, in a Mediterranean mixed pinewood

The relationships between the main abiotic environmental variables, food availability, dict, activity and home range size of the fox in a Mediterranean mixed pinewood were assessed. Food habits were determined by faecal analysis on a weekly basis. Food availability was measured by weekly censuses. Radio-tracking allowed the detection of fox movements and activity. Individual differences shown by a sample of four radio-tagged foxes were analysed. Juniper berries (Juniperus oxycedrus) were the staple of the diet during the year, except in summer. Insects, mainly nocturnal Orthoptera and cicada larvae (Cicada orni), were the main prey in the warm season. Large vertebrates, mostly wild boars (Sus scrofa), were scavenged in winter. In the warm season foxes' activity depended largely on the pattern of activity of prey. Food habits tended to depend on food availability, which, in turn was mainly influenced by temperature. In spite of habitat similarity, individual differences in food habits were detected within the same season. Home ranges were larger in pinewood than in neighbouring heterogeneous habitats. Individual home range sizes were: (i) directly correlated to Orthoptera abundance and distribution; (ii) inversely correlated to the abundance of cicada larvae in diet. Resident males may exist in fox society, exploiting other males' territories when good clumped food resources are available.     

Determinants of bird species richness: role of climate and vegetation structure at a regional scale

We examined the respective roles of climate and vegetation structure on geographical variation in bird species richness. The Province of Buenos Aires (central-eastern Argentina) was divided into 146 squares of 50 km on a side. For each square we evaluated the number of bird species, the value of thirteen climatic variables, and the value of a vegetation strata index. The climatic matrix was analyzed by Principal Component Analysis (PCA), and the first factors resulting from PCA were considered as multifactorial climatic gradients. Simple and Partial Correlation Analysis among bird species richness, vegetation strata, and the first two factors derived from PCA (65% of total variation) indicated that bird richness distribution was determined by the availability of vegetation strata, associated with different vegetation types that, at the same time, were influenced by the climatic conditions summarized in the first climatic factor (a gradient of precipitation, relative humidity, annual termical amplitude, and frost occurrence). This relationships reflect the complexity of factors that can act directly as well as indirectly on the geographical patterns in species richness. Also, we evaluated the importance of study scale comparing our results with previous studies at macrogeographic and local scales, found out that the vegetation structure was the principal determinant of bird species richness at this three geographical scales.     

Effects of sampling time,species richness and observer on the exhaustiveness of plant censuses

Question: How may sampling time affect exhaustiveness of vegetation censuses in interaction with observer effect and quadrat species richness? Location: French lowland forests. Methods: Two data sets comprised of 75 timed, one‐hour censuses of vascular plants carried out by five observers on 24 400‐m² forest quadrats were analysed using mixed‐effect models. Results: The level of exhaustiveness increased in a semi‐logarithmic way with sampling time and decreased with quadrat species richness. After one hour, 20 to 30% of the species remained undetected by single observers. This proportion varied among observers and the discrepancy increased with increasing sampling time. Fixing the sampling time may make richness estimates vary less between observers but the time limit should be at least 30 min to reduce the bias in exhaustiveness between rich and poor quadrats. Conclusions We advocate the use of sampling methods based on spatially or temporally‐replicated censuses and statistical analyses that correct for the lack of census exhaustiveness in vegetation studies.     

Daily variations ofAlternaria spores in the city of Murcia (semi-arid southeastern Spain)

Annual variations in the abundance ofAlternaria spores were related to the length of the spore period for data from Murcia (southeastern Spain). To understand the relationship between the number of spores and climatic factors,Alternaria spore counts for March 1993 to February 1994 were examined by means of correlation and regression analyses with fourteen different weather parameters. The results indicated that there was a tendency forAlternaria spore concentrations to increase with increases in temperature, wind speed and hours of sunshine. Negative correlations were observed with air pressure, wind direction and humidity. Theoretical curves forAlternaria spore counts are given in relation to temperatures during the period studied.     

Determining Observer Reliability in Counts of River Otter Tracks

ABSTRACT In many research projects, reliability of collected data is dependent on reliability of field observers. However, it is uncommon for observer reliability to be either measured or reported in wildlife research. We tested whether observer skill affected outcomes of a northern river otter (Lontra canadensis) track survey conducted by the Texas Parks and Wildlife Department. Observers recorded presence of tracks at bridge sites (n = 250) throughout a 27-county region in east Texas, USA. Logistic regression indicated that observers were significantly associated with frequency of reported otter tracks. Because observers were not assigned to bridges at random, we tested and found associations between the bridges surveyed by each observer (SURVEY ROUTE) and habitat variables (WATERSHED, VEGETATION-TYPE, WATER-TYPE, BRIDGE-AREA) that may have influenced otter presence and probability of detection. A standardized tracker evaluation procedure indicated that experienced observers (n = 7) misidentified 37% of otter tracks. Additionally, 26% of tracks from species determined to be “otter-like” were misidentified as otter tracks. We recommend that observer skill in identification of animal tracks and other indirect signs be measured to detect and reduce observer errors in wildlife monitoring.     

Seasonal variation in prey preference,diet partitioning and niche breadth in a rich large carnivore guild

Large carnivore community structure is affected by direct and indirect interactions between intra-guild members. Co-existence between different species within a carnivore guild may occur through diet, habitat or temporal partitioning. Since carnivore species are highly dependent on availability and accessibility of prey, diet partitioning is potentially one of the most important mechanisms in allowing carnivores to co-exist. Intra-guild interactions may vary over time as carnivore prey preference and diet overlap can change due to seasonal changes in resource availability. We conducted scat analysis to compare the seasonal changes in prey preference, diet partitioning and niche breadth of four large carnivore species, namely leopard Panthera pardus, spotted hyena Crocuta crocuta, brown hyena Parahyaena brunnea and wild dog Lycaon pictus in central Tuli, Botswana. Large carnivores in central Tuli display a high dietary overlap, with spotted hyena and brown hyena displaying almost complete dietary overlap and the other carnivore species displaying slightly lower but still significant dietary overlap. Dietary niche breadth for both hyena species was high possibly due to their flexible foraging strategies, including scavenging, while leopard and wild dog showed a relatively low niche breadth, suggesting a more specialised diet. High dietary overlap in central Tuli is possibly explained by the high abundance of prey species in the area thereby reducing competition pressure between carnivore species. Our research highlights the need to assess the influence of diet partitioning in structuring large carnivore communities across multiple study sites, by demonstrating that in prey rich environments, the need for diet partitioning by carnivores to avoid competition may be limited.